Protective connection device in electrode wiring of electrolytic cells

ABSTRACT

The anode of an electrolytic cell is connected to a bus bar through a connection device in which a lead wire connected at one end to the bus bar is connected at the other end to the anode through a solder joint, on which a continuous separating force is exerted by a spring-separating mechanism. When an excess current due to a short circuit in the electrolytic circuit flows through the lead wire, the solder melts and the joint is broken by the separating mechanism to break the circuit, whereby the electrolytic circuit parts are protected.

[ Feb. 22, 1972 United States Patent Otake et al.

[54] PROTECTIVE CONNECTION DEVICE B N m M M G S mm .9 km MN u 6., B

F 0 GS NL IL, E I C Em w L T0 CR ET LC m mE 3,420,217 1/1969 Powell et [72] Inventors: Naokichi Otake; Yutaka Yamanobe, both 3 519 972 7/1970 -m 9f Iwaki; Kflmmi Siim, Takahasi; 3,543,211 11/1970 Dahl.... nika'suusubalwakiallfilapm 2,775,669 12/1956 Primary Examiner-Bemard A. Gilheany Assistant Examiner-Dewitt M. Morgan Attorney-Wenderoth, Lind 8L Ponack [22] Filed:

[ ABSTRACT The anode of an electrolytic cell is connected to a bus bar Foreign Aiiplication Priority Data Apr. 16, 1969 through a connection device in which a lead wire connected at one end to the bus bar is connected at the other end to the anode through a solder joint, on which a continuous separating force is exerted by a springseparating mechanism. When .337 ll 142 143 152 157 an excess current due to a short circuit in the electrolytic cir- 337/402, 403, 404, 407, 408, 409, 41 1 417 Cuit flows through the lead wire, the solder melts and the joint is broken by the separating mechanism to break the circuit, whereby the electrolytic circuit parts are protected.

[51] Int. [58] Field of l Claims, 2 Drawing Figures PATENTEDFEBZZ m2 SHEET 1 [IF 2 FIG.

NAOKICHI OTAKE, YUTAKA YAMANOBE, KA'IUM'I SIINA and KUNIKATSU USUBA,

INVENTOR H ATTORNEYS BACKGROUND OF THE INVENTION This invention relates generally to electrochemical processes and apparatuses and more particularly to a new protective connection device for connecting an electrode in an electrolytic cell to a power-supply conductor and operating promptly, when a short circuit occurs in the electrolytic circuit, to break the connection and thereby to protect various parts of the electrolytic apparatus.

In electrolysis to produce sodium hydroxide by the mercury process, for example, substances such as mercury butter" formed in the electrolytic cell and particles of graphite broken off from the electrode collect on the mercury cathode and frequently cause short circuiting between the two electrodes. When a short circuit of this nature occurs, it causes the shortcircuited parts and the lead wire connecting the bus bar and the anode to become heated and gives rise to various risks, failures, and losses, the most serious of which are as follows.

1. Danger of explosion in the electrolytic cell induced by ignition of the short-circuited parts.

2. Burning and breaking of a lead wire due to ignition thereof.

3. Not only electric current loss due to the short circuit but also irregularity of current distribution and increase in electrolytic cell voltage.

4. Separation of the coupling part of an electrode bar and the electrode or damage to the electrode due to heating and expanding of the electrode bar.

5. Increase in the electrical resistance of the coupling part between an electrode bar and a cathode and damage to the electrode bar due to burning.

6. Breakage of an electrode, from which a large fragment falls and causes short circuiting between other anodes and cathodes, whereby other electrodes are damaged one after another. I

7. Short circuit between an electrode and an electrolytic plate to cause damage to the electrolytic plate.

The economic loss due to expenditure for equipment materials, starting materials, and repair costs and due to stoppage of the operation of the electrolytic cell which accompany these failures is great. In electrolytic cells for aluminum production, also, there are instances of short circuiting between electrodes due to breaking off of graphite electrodes and increase in an aluminum layer formed within each cell, in which instances similar losses and failures are also liable to arise.

Furthermore, in the case where the electrodes of an alkalisalt electrolytic cell are changed to permanent electrodes such as titanium-platinum electrodes, a reduction in malfunctioning due to short circuits can be expected. However, if a short circuit failure should occur, there would be the risk of a great loss due to damage to expensive electrodes.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a protective connection device of simple organization and operation which is suitable for use in the wiring of electrodes in an electrolytic apparatus and operates automatically and promptly,

when a short circuit occurs in the apparatus, to break the circuit thereof and thereby to prevent the above-described failures and losses.

'The foregoing object can be achieved according to the invention by a protective connection device in which a lead-wire conductor is connected to a conductor from an electrode by means of a joining metal of low melting point, and a separating mechanism is provided to exert on the two conductors a continual force urging them apart, whereby, when an excessive current due to a short circuit flows through the conductors, the joining metal melts and the conductors are separated to break the electrolytic circuit.

The nature, principle, and utility of the invention are more fully indicated in the following detailed description with respect to a preferred embodiment thereof as illustrated by the accompanying drawing, in which like parts are designated by like reference numerals.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is an elevation partly in section and with parts 'cut away, showing one example of an anode conneCtion device according to the invention in connected state;

FIG. 2 is a similar view showing the same device in disconnected or circuit-breaking state.

DETAILED DESCRIPTION Referring to FIG. 1, the anode connection device illustrated therein in normal connective state connects a bus bar 8 to an anode bar 1 connected at its lower end to an anode (not shown). The upper end of the anode bar I is tapped and is connected to the threaded lower end 5 of a coupling plate 2 screwed thereinto. The upper end of the coupling plate 2 is in the form of a cup-shaped socket 3, the inner surface of which is conneCted by solder 7 to one end of a flexible lead strap 6 made up of several laminated layers of copper sheets 4. The other end of this lead strap 6 is connected by a bolt 9 to the bus bar 8.

On one hand, the coupling plate 2 and lead strap 6 are respectively fixed by bolts 11 and 12 to coaxially opposed lower and upper heads 13 and 14 of a spring-powered separating mechanism 10. This separating mechanism 10 is in the form of an extensible strut and comprises the coaxial lower and upper heads 13 and 14, a guide rod 16 fixed at its upper part to the lower part of the upper head 14 by a screw connection 17, an electrically insulating gland or bush 18 made of a material such as polyvinyl chloride and having a central bore slidably engaged with the lower end of the guide rod [6 when theconnection device is in the connected state shown in FIG. I, and a coil compression spring 15 disposed around the guide rod 16 and retained at its upper and lower ends by socket recesses formed in the upper head 14 and the insulating bush 18. The spring 15 is maintained compressed and therefore is continuously exerting a great force tending to separate the upper and lower heads 14 and 13 when the connection device is in the normal connecting state indicated in FIG. 1.

The insulating bush 18 serves to insulate the upper head I4 and parts connected thereto from the lower head 13 and parts connected thereto thereby to prevent electric current from flowing through the separating mechanism 10 irrespective of the state of the connection device.

When a short circuit occurs between the cell electrodes, and lead strap 6 of low current carrying capacity becomes heated, the heat thus generated first melts solder 7 in socket 3 of coupling plate 2, whereby the connecting strength of this solder joint is weakened. On one hand, lead strap 6' has ample flexibility, and spring 15 is exerting a great force urging heads 14 and 13 apart as mentioned above. Consequently, when solder 7 in socket 3 melts, the lower end of lead strap 6 is promptly extracted out of and pulled apart from socket'3, and the parts of the connection device assume the state indicated in FIG. 2, whereby the electrode current is cut off. Thus, destructive results which would otherwise be caused by the short circuit are effectively prevented.

The connection device of the invention, as illustrated above by one example thereof, is of simple organization and operation affording low cost of manufacture and maintenance. Furthermore, after this device has operated in response to a short circuit, it can be readily restored to its original state without any damage whatsoever after the cause of the short circuit has been removed.

It should be understood, of course that the foregbing'disclosure. relates to only a preferred embodiment of the invention and. that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention. For example, while the cupshaped socket 3 is connected to the anode bar 1 by way of a coupling plate 2 in the above-described example, the socket 3 may be welded directly onto the anode bar in some cases.

We claim:

1. A protective connection device for the wiring of an electrode bar in an electrolytic cell, which comprises; an electrode bar; a vessel-shaped socket connected to said electrode bar through a coupling means; a flexible lead-wire conductor connected at one end thereof to the inner surface of said socket by means of a metal of low melting point; and a separating means comprising a first head having an insulating bush secured interiorly thereof and secured to said coupling means,

a second head secured to said lead-wire conductor, a guide rod fixed at one end thereof to said second head and adapted to engage slidably with a guide bore in said bush, and a spring positioned between said first and second heads and maintained in a deflected state for exerting a force for urging said first and second heads apart, said force tending to cause separation of said end of the conductor and the socket, whereby, when an excessive electric current flows through said conductor, and melts said low melting metal, said force causes such separation, said separating mechanism being provided with at least one insulating member to prevent flow of electric current between the lead-wire conductor and the socket thus separated. 

1. A protective connection device for the wiring of an electrode bar in an electrolytic cell, which comprises; an electrode bar; a vessel-shaped socket connected to said electrode bar through a coupling means; a flexible lead-wire conductor connected at one end thereof to the inner surface of said socket by means of a metal of low melting point; and a separating means comprising a first head having an insulating bush secured interiorly thereof and secured to said coupling means, a second head secured to said lead-wire conduCtor, a guide rod fixed at one end thereof to said second head and adapted to engage slidably with a guide bore in said bush, and a spring positioned between said first and second heads and maintained in a deflected state for exerting a force for urging said first and second heads apart, said force tending to cause separation of said end of the conductor and the socket, whereby, when an excessive electric current flows through said conductor, and melts said low melting metal, said force causes such separation, said separating mechanism being provided with at least one insulating member to prevent flow of electric current between the lead-wire conductor and the socket thus separated. 